Grass mowing machines may have grass collection containers connected to the discharge duct of a mower deck. The discharge duct may extend from the mower deck, upwardly and rearwardly to a collection container mounted at or on the rear end of the vehicle. A variety of different grass collection containers are available.
For example, grass collection containers for grass mowing machines may be flexible fabric-type bags or hoppers. These grass collection containers may be relatively simple, light weight and economical. The fabric may be a mesh or other air permeable material to allow air flow through the bag while trapping grass clippings. The bags or hoppers may be carried or supported by a frame attached to the rear of the vehicle, and may be covered by a solid top cover. U.S. Pat. Nos. 3,722,192; 3,874,152; 3,971,198; 4,054,023; 4,173,111; 4,377,063; 4,393,645; 4,522,019; 5,195,310; 5,564,265; 6,226,970; and 6,546,710 relate generally to flexible fabric grass collection containers.
Alternatively, grass collection containers may be solid or rigid cans or containers. The solid containers may be plastic, metal or similar material. Solid grass collection containers also require an air outlet and tend to be more complex, heavy and costly than mesh bags or hoppers. U.S. Pat. Nos. 3,199,277; 4,265,079; 4,399,647; 4,426,830; 4,631,909; 4,648,238; and 5,074,106 relate generally to solid or rigid grass collection containers. Some grass collection containers also may have a liner inside an outer bag or container. U.S. Pat. Nos. 3,958,401; 3,971,198; and 4,054,023 relate generally to grass collection containers with disposable inner bags.
Some grass mowing machines include an auxiliary fan or blower to help propel clippings from the mower deck through a discharge duct into a grass collection container. U.S. Pat. Nos. 4,104,852; 4,193,249; 4,426,830; and 5,224,327 relate generally to auxiliary fans or blowers for grass collection.
Air flow into and through grass collection containers contributes to the noise of grass mowing machines. In recent years, regulations limit the noise generated by these machines. Attempts to reduce or limit the noise have included decreasing the speed of rotary cutting blades and reducing the wing or lift of the blades. However, decreasing blade speed or lift tends to impair cutting performance and limits the effectiveness of grass collection. There continues to be a need to reduce or limit the noise from grass mowing machines without sacrificing cut quality or collection. A low cost, effective solution is needed to reduce noise from these machines.
Grass clippings may be collected under a variety of conditions, including adverse conditions such as wet or thick grass. To handle adverse conditions, grass mowing machines may be designed with increased mower blade speeds, and improvements may be made to the air handling properties of the grass collection containers. There is a need to reduce the noise of grass mowing machines that perform well in adverse conditions, without decreasing mower blade speeds or air handling properties of grass collection containers.